EVAPOTRANSPIRATION AS AFFECTED BY SOIL MOISTURE AND FERTILIZER USE

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EVAPOTRANSPIRATION AS AFFECTED BY SOIL MOISTURE AND FERTILIZER USE

D.P. SINGH·

Institute for Cereal Production, Martin-Luther-University, Halle-Wittenberg, German Democratic Republic

Received on 1une 10, 1977

SUMMARY

A series of pot and field experiments conducted on sandy loam soil revealed that an increase in soil water supply increased evapotranspiration (ET) of cereal crops signifi­ cantly. Application of fertilizers also increased ET but only slightly. Efficiency of water per unit weight of yield reduced with increase in soil water supply. Adequately nourished plants showed reduction in width of stoma tal aperture and used water most efficiently than poorly nourished plants. Only judicious use of water and fertilizers might improve each other's efficiency.

INTR.ODUCTION

Enormous researeh work has been done in the past on fertilizer use in relation to irrigation. Effects of water supply on ET have been well understood (Ketellapper, 1963; Salim and Todd, 1965; Raschke, 1975). However, conflicting reports are available in the literature about the influence of fertilizers on ET (Arland, 1952;. Viets, 1%2; Zwicker, 1963; Frommhold, 1966; Jaeger, 1%6 a; Shimshi,1967; Jung, 1970; Lal and Sharma, 1976; Mehrotra et of., 1976). Therefore, in this paper an attempt has been made to examine critically the effects of soil moisture and fertilizers on ET of some important cereal crops.

MATBRlAL AND METHODS

A series of pot and field experiments were conducted with different soil moisture and nitrogen levels on autumn rye (var. petka), spring wheat (var. carola), winter wheat (var. poros), spring barley (var. astacus) and oats (var. astor) from 1969 to 1971 at Institute for Cereal Production of Martin-Luther-University, Halle-Wittenberg (German Democratic Republic). This tract belongs to a temperate climate with average annual precipitation 560 mm and mean annual temperature 8.7°C. The soil used for experiments was sandy loam in texture (27.86% coarse sand, 40.32"10 fine sand, 19.19% silt and 12.63% . clay), medium fertile (90.9 mg total N, 8.7 mg available P, 10.8 mg available K per 100 g

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II

254 D.P. SINGH

soil) and slightly acidic in reaction (6.2 pH). It retained 25%. 19.5% and 5.0% moisture on dry weight basis respectively at maximum water holding capacity of pots. field capacity and permanent wilting point.

Nitrogen applied to autumn rye (0.5. 1.5 g N/pot) and spring wheat (1.0 g N/pot in 1970~ 1.2, 1.8 g N/pot in 1971) was mixed in 6 kg dry sieved soil of each pot in the form of N~N03 solution at the time of sowing. Autumn rye was sown on 19th August, 1969 and harvested on 29th October, 1969. Spring wheat was sown during 1970 and 1971 in the first week of April and harvested in the second week of August. Field crops received lower quantity of nitrogen (Fig. 1) along with phosphate and potassium at the time of sowing in the first week of April (winter wheat sown in October, 1969 also received nitrogen in April, 1970) and remaining quantity of nitrogen was top dressed at jointing stage (fourth week: of May to first week of June) only to treatments receiving higher levels of nitrogen. Field crops were harvested in August.

Crops in pot and field experiments were irrigated uniformly upto tiIlering stage of growth. Thereafter, different levels of available soil moisture (% ASM) in field experiments (Fig. 1) and of water holding capacity (% WHC) in pot experiments (Fig. 2'for spring wheat; Fig. 5 for autumn rye) were maintained through irrigation.

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FIG. 1. Effect of soU moisture and nitrogen levels on evapotranspiration of wheat, barley and oats (Field experiment, 1970).

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BVAPOTRANSPIllATION IN CEREAL CROPS 255

collodium solution in 1 : 2 ratio of alcohol and ether respectively) taken on both sides of fully developed upper 1/3 por.tion of leaf blades of the same age and position on the stem. For each treatment, 100 stomata from five different leaves were measured. R-Value and stomatal opening were measured twice a week during mid-day hours on clear days.

ET was determined from soil water balance studies, rainfall and irrigation data in .field experiments. In pot experiments, ET was measured as weight deficit in pots through daily loss of water. ET per 'g' yield was worked out on the basis of biological yield (grain and straw) and total amount of water applied during growth period.

RESULTS AND DISCUSSION

Effect of soil moisture on ET.-An increase in soil water supply increased ET of spring wheat (Table I), winter wheat, oats and barley significantly (Fig. 1). Increase of soil

Table J. Effect of soil moisture and nitrogen levels on ET, plant water balance, root . growth and yield of spring wheat (Pot experiment, 1971)

ETlpot/day ET/g yield/day R-Value Root wt./pot yield/pot (g)

Treatments (g) (g) (%) (g)

grain straw Soil moisture levels

(% WHC)

35 273.0 3.30 7.4 5.0 31.0 46.5

SO 322.7 3.51 6.9 5.9 33.4 52.7

65 385.1 3.68 6.6 6.9 36.6 61.0

CD 5% 22.5 0.06 0.4 0.3 1.6 2.9

Nitrogen levels (N/pot in g)

1.2 249.7 3.52 7.4 SA 20.9 41.6

t.8 395.3 3.34 6.5 6.4 46.4 65.2

CD 5% ]8.7 0.04 0.3 0.3 1.3 2.4

water content also improved plant water balance, width of stomata, leaf area and root growth of spring wheat (Fig. 2 and Table I). Thus, more :flow of water from soil via plants to atmosphere due to better growth of roots, lesser stomatal resistance and greater expan­ sion of leaves at higher soil moisture might have increased transpiration. Greater vapour pressure gradient between soil-plant surfaces and atmosphere at more moist soil would have also caused an increase in ET. The relation of stomatal width and leaf area to ET, which is linear, have been demonstrated in Fig. 3. Similar results have been reported by Cowan (1965) and Salim and Todd (1965).

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256 D.P. SINGH

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FtG. 3. Effect of leaf area and width of stomata on evapotransI,liration of spriDI wheat (Pot experiment, 1970).

at near potential rate when water is adequate while yield is not because yield is a comple,X phenomenon depending to a great extent on several other factors.

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EVAPOTRANSPIRATION IN CEREAL CROPS 257

FIG. 4. Effect of soil moisture levels and width of stomata on yield of sprin, wheat (Pot

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FIG. 5. Effect of soil moisture and nitrogen levels on plant water balance and width of stomata of rye (Pot experiment, 1969).

these respects (Table I, Singh, 1973a). Zwicker (1963) and Jaeger (l966b) reported that an increase in quantity of fertilizers in oats (0.25, 0.5, 1.0, 2.0, 3.0 g N/pot in Zwicker's experiment; control, 30·30·60, 60·60-90, 120-90-120 kg N, P20S, K20/ha respectively in Jaeger's experiment) reduced K+ and increased Ct-contents in cell sap significantly. His­ tochemical as well as microprobe studies demonstrated a linear dependency of stomatal opening on the K + content in guard cells, while increase in CI- content in guard cells reduced width of stomatal aperture by balancing the charges ofK+ ions (Raschke, 1975). Also the plants richly supplied with nitrogen had more organic colloids with many hydro- < philic radicals, which increased water holding capacity and water content ofleaves (Zwicker

1963; Jaeger, 1966a; Jung, 1970). Reduction in width of stomata and transpiration as well as improvement in plant water< balance with increasing quantity offertilizers upto optimum level can be explained on the basis of observations of the above and other workers (Arland experiment, 1970).

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1952; Frommhold, 1966). Therefore, an increase in the transpirational area (plant density, leaf area) of adequantely fertilized plants over poorly nourished crops might not increase ET proportionately due to reduction in width of stomatal aperture at optimum level of fertility.

Efficiency of water to produce unit plant dry weight of spring wheat increased with increase in the quantity of nitrogen (Table I). A slight increase in ET due to fertilizer application in winter wheat, oats and barley brought significant improvement in grain and straw yields over treatment without fertilizer application (Fig. 1, Singh, 1973b, 1974). Viets (1962) also concluded that fertilizers increase consumptive use only slightly, if at all and water use efficiency can be greatly increased if fertilizers increase yield. Similar results have been reported by Lal and Sharma (1976) and Mehrotra et aI., (1976). Zwjcker (1963) observed that optimum dose of fertilizers resulted in minimum diurnal and seasonal fluc­ tuations of plant-water balance (stable hydrature), relative minimum transpiration and maximum yield of oats. Well nourished plants showed more proportion offcee water dur­ ing mild weather conditions and more proportion of bound water during high evaporative demand, thus lesser deterioration of plant-water balance and depression of photosynthesis during mid-day. Poorly nourished plants, on the other hand, had lesser control on plant­ water balance and transpiration (rigid or inelastic), thus suffered more from water deficit under adverse weather conditions.

Effect ofsoil moisture and fertilizers on ET.-In general, an increase in soil moisture and fertilizer levels increased ET per unit land area in aU tested crops. However, water use per unit quantity of yield at certain level of soil moisture supply varied with variations in quantity of fertilizer. An increase in soil moisture supply increased ET per g yield of spring wheat significantly only at lower levels of nitrogen (Table II). Similarly, in field

Table II. Effect ofsoil moisture and nitrogen levels on ET (gIg yieldlday) of spring wheat (Pot experiment 1970 and 1971)

Soil moisture levels (% WHC) Nitrogen levels

(N/pot in g) 35 50 65

5.32 7.00 7.69

1.0

3.38 3.54 3.78

1.2

3.30 3.34 3.32

1.S

0.08 CD 5%·

.Por comparing the interactional effects of 1.2 and 1.8 g N/pot

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EVAPOTRANSPIRATION IN CDR.BAL CROPS 259

forage grasses (Jung, 1970). Thus, judicious use of water and fertilizer is essential to build up balanced water transport system in cereals for increasing their yield and water use efficiency.

ACKNOWLEDGEMENT

Grateful thanks are due to Dr. H.J. Wicke, Director and Head, Institute for Cereal Production, Martin-Luther-University, Halle-Wittenberg (G.D.R.) for his keen interest, timely help and continued encouragement during the course of investigations.

REFER.ENCES

Arland, A. (1952). Die Anwenung der Mineraldunger im Blickfelde der Anwelkmethode. Dtsch. Landw.,

3: 409-12.

Cowan, I. R. (1961). TransPort of water in the soil-plant-atmosphere system. J. Appl. Bcol., 2: 221-39. Frommhold, I. (1966). Untersuchungen fiber den Einfluss Von Stickstoff-und Kaliummangel auf das

Verhalten der Stomata von Hafer und Runkelrube unter besonderer Berucksichtigung der Anwelktranspiration. Wiss. Z. KMU Leipzig., 15: 83-94.

Jaeger, S. (1966 a). Der Wasserhaushalt von Avena sativa L. bei steigender Mineralvolludu·ngung. I. Mitt. okologische Unterschunp. Plant and Soil, 24: 24-32.

(1966 b). Der. Wasserhaushalt von Avana sativa L. bei steigender Mineralvolldungung. U. Hydratur und Pressaftanalysen. Plant and Soil, 24: 201-12.

Jung, E. (1970). Der Wasserhaushalt der Hauptbestandsbildner einer Weidegrasnarbe unter dem Einfluss von Beregnung, Dungung und Nutzungszeit und sich daraus ergebende veranderungen des Pflanzenbestandes. Diss. Humboldt Univ. Berlin. .

Ketellapper, H. J. (1963). Stomatal Physiology. Ann. Rev. PI. Physiol. 14: 249-70.

Lat, P. and Sharma, K.C. (1976). Water use studies in two dwarf varieties of wheat grown at dilferentlevels of soil moisture and nitrogen under shallow water table conditions. Indian J. Agron.• 21: 453-59. Lapina, L.R. (1967). On the effect and after effect of high iso-osmotic concentrations of NaCI and dex­

trane on horse bean plants. Fisiol. Rast., 14: 319-72 (Russ.).

Mehrotra, O.N.. Pal, M. and Singh, B. (1976). Effect of irrigation, fertility and seed rates on yield and water requirem~nts of dwarf wheat in eastern Uttar Pradesh. Indian J. Agron.,21: 141-44.

Raschke, K. (1975). Stomatal action. Ann. Rev. Pl. Physiol., 26: 309-40.

Salim, M.H. and Todd, G.W. (1965). Transpiration patterns of wheat, batley and oat seedlings under

v~rying conditions of soil moisture. Agron. J.• 57: 593-96.

Shimshi, D. (1967). Leaf chlorOSIS and stomatal aperture. New Phytol., 66: 455-61.

Singh, D.P. (1973 a). Effect of irrigation and manuring on water status of cereals. Indian J. Plant Physiol.,

16: 105-15.

---(1973 b). Response of winter wheat and spring barley to irrigation and nitrogen fertilization.

B.Y.J. Agri. Sci. Res. 15: 8-10.

---(1974). Relation of refractometer value of cell sap to growth and yield of cereals. Indian J.

Plant Physiol., 17: 28-35.

---(1977). Using internal plant water balance as criterion for scheduling irrigation. Indian J. Plant Physiol., lO: 63-68.

Slatyer, R.O. (1961). E:ifect of several osmotic substances on the water relationship of tomato. Aust. J.

Boil. Sci., 14: 519-40.

___---(1967). Plant water relationships. Academic Press Inc. New York. 293-94.

Stanberry, C.O. and Lowery, M. (1965). Barley prnduction under various nitrogen and moisture levels.

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260 D.P. SINGH

,

Viets, F.O., Jr. (1962). Fertilizers and efficient use of water. Adv. Agron., 14: 223·64.

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Wicke, H.J., Stock, H.O. and Singh, D.P. (1972). Studies on the effect of sprinkler irrigation on the yield fonnation of cereal crops. Arch. Acker. u. Plfanzenbau u. Bodenkund., 17: 573-84 (German). Zwicker, R. (1963). Untersuchungen zur Arlandschen Anwelkmethode unter besonderer Berucksichtigung

Figure

FIG. 1. oats (Field experiment, Effect of soU moisture and nitrogen levels on evapotranspiration of wheat, barley and 1970)
FIG. 1. oats (Field experiment, Effect of soU moisture and nitrogen levels on evapotranspiration of wheat, barley and 1970) p.2
Table J. Effect ofsoil moisture and nitrogen levels on ET, plant water balance, root

Table J.

Effect ofsoil moisture and nitrogen levels on ET, plant water balance, root p.3
FIG. 5. of rye (Pot Effect of soil moisture and nitrogen levels on plant water balance and width of stomata experiment, 1969)
FIG. 5. of rye (Pot Effect of soil moisture and nitrogen levels on plant water balance and width of stomata experiment, 1969) p.5
FIG. 4. Effect of soil moisture levels and width of stomata on yield of sprin, wheat (Pot experiment,
FIG. 4. Effect of soil moisture levels and width of stomata on yield of sprin, wheat (Pot experiment, p.5
Table II. Effect ofsoil moisture and nitrogen levels on ET (gIg yieldlday) ofspring

Table II.

Effect ofsoil moisture and nitrogen levels on ET (gIg yieldlday) ofspring p.6

References

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